Two detectives pulled a bag of documents and personal effects from Soltys' North Highlands home outside Sacramento on Monday.

'We don't know whether we've got any gems among the items yet,' said FBI spokesman Nick Rossi. 'We're looking for anything, basically, scraps that can tell us where he might have gone.'

Sacramento County Sheriff's Sgt James Lewis said an initial review found no new leads.

Police plan to call in a profiler this week from the FBI's National Centre for the Analysis of Violent Crime at Quantico, Virginia, or the California Department of Justice, whichever can respond most quickly.

Usually profilers are used to help identify a criminal, Lewis noted. In this case, police believe Soltys to be the killer, but hope a profiler can help unravel the actions of a man whose motives and behaviour are baffling even experienced homicide detectives.

Meanwhile, an incident report made public yesterday says a neighbour tried to shield Soltys' pregnant wife, Lyubov, after she was stabbed by her husband on August 20.

Roman Kravchenko and his wife were home when Lyubov burst in just before 10am, bleeding heavily from several stab wounds, according to the statement accompanying Soltys' outstanding arrest warrant.

Soltys soon followed, brandishing a knife, the statement says. Kravchenko fended him off with a chair while he, his wife, and Lyubov escaped to the garage. Kravchenko held the garage door closed until Soltys stopped trying to break in, then ran to a neighbour's house to call police.

Police found Lyubov dead on Kravchenko's kitchen floor.

About 30 detectives completed a door-to-door canvass of the Sacramento County area where Soltys was last seen a week ago, then shifted their search to the Rancho Cordova neighbourhood where Soltys is alleged to have stabbed to death his aunt, uncle and two young cousins, shortly after police say he murdered his wife. Soltys' three-year-old son was later found dead a few miles away.

They are questioning members of the Ukrainian-Russian community and checking on their welfare.